Apparatus for producing scored lines in a film

ABSTRACT

The present invention makes it possible to produce at least one scored line in at least one plastic outer layer of a film. The device of the invention includes bearing surface for the film and at least one projection for forming the scored line by penetration of the projection into the plastic layer when the film is in position against the said bearing surface. The projections may be arranged in the form of ribs on one or more coaxial rollers. The projections may form the scored line by ultrasonic plastic flow, the film being compressed between a sonotrode and the rollers. The invention provides methods using these devices and it also provides films having scored lines, and packages having scored lines.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a National Stage of PCT/EP2003/006492 filed on Jun.19, 2003 claiming priority to EP 02291535.9 filed Jun. 19, 2002 and U.S.Ser. No. 10/342,603 filed Jan. 15, 2003.

TECHNICAL FIELD

The present invention relates to a device for producing at least onescored line in at least one plastic outer layer of a film. The inventionalso relates to a method for producing at least one scored line in justa first plastic layer of a film comprising at least a second layer. Theinvention also relates to a method of manufacturing a packaging. Theinvention also relates to a film and a packaging having a scored line.

BACKGROUND OF THE INVENTION

The invention has a particularly advantageous application in theproduction of pouches or bags containing foodstuffs, especially animalfoodstuffs, such pouches or bags being designed to be hermeticallysealed by welding and heat-treated after they have been filled andclosed.

Currently, such packagings have various shapes. They may be flat withthree or fours welds, or gusset-shaped with three welded sides or threewelded sides and a welded bottom in the shape of a gusset. Suchpackagings may also comprise two side gussets or two gussets positionedat the top and bottom of the packaging with welded side edges.

These packagings can be sterilized by being heated in a moist atmosphereunder pressure. To withstand such a heat treatment, they are producedfrom one or more film(s) having a particular structure.

More particularly, they are generally manufactured from one or morefilm(s), each film comprising an upper layer and a lower layer designedto form the outer and inner faces of the said packagings, made ofplastic, and a central layer sandwiched between the said upper and lowerlayers, the central layer being made from a light metal. In general, theupper layer is a layer of polyethylene terephthalate which may or maynot be combined with a polyamide layer. The central layer is made fromaluminum and the lower layer is a polypropylene layer which may or maynot be combined with a polyamide layer. Between each layer, an adhesivecoating is provided which makes it possible to bond the various layerstogether, for example, by lamination.

Furthermore, the polyethylene terephthalate layer can be printed on itsinner face and/or its outer face. Thus, the polyethylene terephthalatelayer generally acts as a printing medium and gives the packaging itsexternal appearance.

The central aluminum layer forms a barrier to gas, especially to oxygenand steam, in order to isolate the substances contained inside thepackaging from the outside. This central layer is weak because of itslow thickness; it is protected by the lower and upper layers.

The polyamide layer forms an anti-perforation layer when this isrequired depending on the subsequent applications of the packaging, andthe polypropylene layer acts as a welding agent for making thepackaging, gives the overall mechanical strength of the packaging andseals the welds of the said packaging.

Such packagings may in particular contain moist solids, liquids or elsea combination of solids and liquids.

Some packagings may comprise a tear-initiating notch on their sideedges. This notch is therefore made in a side weld of the packaging andmakes it possible to open the latter by tearing.

These packagings, which are already known, have certain drawbacks,especially connected with their method of opening.

This is because resorting to a cutting tool such as a pair of scissorsor knife lacks practicality, it being possible, for example, for thistool to be soiled by the product contained inside the packaging.

When the packaging can be opened by a tear initiated using atear-initiating notch, the tear force has to be relatively high andsometimes requires use of a tool.

In fact, the tear force of a multilayer film generally depends on thetear force of the materials forming the packaging and on the adhesiveforce between the various layers forming the said packaging, forceswhich can be altered after preservation treatment thereof.

The tear direction is generally propagated in the walls of the packagingin an undirected manner. Thus, either partial opening of the packagingor a tear below the level of the product contained in the packaging isthen obtained, which causes an undesired spill of this product.

To try to alleviate the aforementioned drawbacks, mainly linked to theopening of these packagings, packagings which have laser producedscoring on the outer faces of their walls have already been proposed.Such packagings are especially described in documents EP-A-540 184 andEP-A-473 517. However, the main drawback of this scoring carried out byapplying a laser beam to the outer face of the packaging walls is thatof impairing the external appearance of the packaging once said scoringhas been carried out.

Document U.S. Pat. No. 5,000,321 also discloses a packaging whichcomprises on its outer and inner faces weakened zones made by means of alaser beam. These weakened zones are obtained by thinning of the layersforming the outer and inner faces of the said packaging.

Furthermore, document EP-A-954 474 proposes a packaging with a scoredline in the form of laser-produced perforation or perforations of theplastic inner layer or layers. The perforations extend to the layer madeof aluminum or other light metal without cutting into it, this layerreflecting the laser beam during the operation of perforating theplastic inner layers with the laser.

Although the technology proposed by this document is satisfactory,nevertheless it is dependent on the presence of the metal film.

More generally, technologies using lasers have a high investment cost,and also a high operational cost associated with the maintenance of thelaser tools and the limited production rate of these technologies.Furthermore, their implementation in the absence of a metal interlayeris very awkward.

BRIEF SUMMARY OF THE INVENTION

The aim of the present invention is to provide an alternative technologyto those known in the prior art in order to produce scored lines inflexible packagings, giving a directed and clean opening of thepackaging.

The invention especially aims to provide an alternative technologyhaving a lower financial investment, which is more economical tooperate, especially by allowing a higher production rate in comparisonwith the technologies using lasers.

The invention further aims to provide a technology capable of producingscored lines in the plastic inner layers of the film forming theflexible packaging even in the case where the film has no metal layer,while being simple to implement.

The invention relates above all, but not only, to flexible packagings,especially in the form of pouches, designed to undergo a preservationtreatment such as those pouches intended to contain liquid or moistsolid foodstuffs, in particular moist animal foodstuffs.

To this end, the present invention provides a device for producing atleast one scored line in at least one plastic material outer layer of afilm, comprising:

-   -   a bearing surface for the film; and    -   at least one projection for forming the scored line by        penetration of the projection into the said plastic material        layer when the film is in position against the said bearing        surface.

The scored line thus produced may be in the form of a continuous ordiscontinuous groove. The term “discontinuous groove” refers to a seriesof grooves or blind holes.

If required, the scored line may be produced in the form of successiveperforations.

The projection is preferably arranged on a support, the scored linebeing formed by relative travel of the film with respect to the support.

The projection may be capable of incising the plastic material layer.

The projection may also cause the plastic of the said layer to flow. Inthis case, the projection preferably causes the plastic of the saidlayer to flow along the scored line in order to form a protuberance onthe said layer along at least one side of the scored line. Theprojection may cause the formation of a bead on the surface of the saidplastic material layer along each side of the scored line, one of thesaid beads being higher than the other of the said beads. It ispreferred that one, of the said beads is at least 30%, preferably atleast 50%, more advantageously at least 100%, higher than the other ofthe said beads.

Alternatively, the projection may cause the formation of a bead on thesurface of the said plastic material layer along each side of the scoredline, wherein the cross-sectional area of one of the said beads isgreater than the cross-sectional area of the other of the said beads,said cross-sectional areas being considered perpendicular to the scoredline. It is preferred that said cross-sectional area of one of the saidbeads is at least 30%, preferably at least 50%, more advantageously atleast 100%, greater than said cross-sectional area of the other of thesaid beads.

Alternatively, the projection causes the formation of a bead on thesurface of the said plastic layer along each side of the scored line,one of the said beads providing a higher mechanical resistance to thesaid plastic layer with respect to the other of the said beads.

Advantageously, the projection may cause the formation of a bead on thesurface of the said plastic layer along just one side of the scoredline.

Of course, if the scored line is of discontinuous type, the bead mayalso be discontinuous.

The projection may especially have an asymmetrical cross section.

The projection (52 a, 52 b; 72 a) may cause the plastic material of thesaid layer to flow along the scored line in order to form a bead on thesaid layer along each side of the scored line, the projection causingmore plastic material to be flowed along one side of the scored linethan along the other side of the scored line.

Preferably, the projection causes the plastic to flow in cooperationwith ultrasound. For this, the device may comprise an anvil and asonotrode for applying ultrasound vibrations to the film when the filmis compressed between the sonotrode and the anvil, the projection beingarranged on the said anvil. The bearing surface is preferably arrangedon the anvil.

Advantageously, the anvil is a wheel mounted so as to rotate, theprojection forming a rib arranged on the circumference of the wheel, therib not extending according to the axial direction of the wheel.

Alternately, the projection may have a straight elongate shape in therun direction of the film, the width and/or the height of the projectionpreferably increasing in the run direction of the film. Furthermore, theprojection may have a cross section with a flat apex parallel to thebearing surface.

The said support may be a roller mounted so as to rotate, the projectionbeing arranged on the circumference of the roller. In this case, theprojection may be arranged on the circumference of a ring, the said ringbeing mounted on the roller. There may be a clearance between the ringand the roller taken at ambient temperature, a heating element making itpossible to clamp the ring on the roller by expansion. Moreover, thebearing surface may be defined by the circumference of a second roller,the axis of which is parallel to the first roller. The first roller mayhave running tracks tensioned against the second roller.

According to another aspect, the invention provides a method forproducing at least one scored line in just a first plastic layer of afilm comprising at least a second layer, the method comprising theproduction of the scored line in the first layer of the film using adevice according to the invention. It will be understood that the firstlayer may possibly be defined by several sublayers of plastic materialswhich may be different, for example polypropylene and polyamide.Preferably, the film is running with respect to the device for producingthe scored line.

According to a preferred embodiment, the said scored line is made afterassembling the first and second layers of the film.

According to another preferred embodiment, the said scored line is madebefore assembling the first and second layers of the film.

According to yet another aspect, the invention provides a method ofmanufacturing a packaging, which may especially be designed to undergo apreservation treatment, from at least one film having a first plasticlayer and at least a second layer, the said second layer forming theouter face of the packaging, which method comprises:

-   -   producing at least one scored line just in the said first layer        of the film according to the aforementioned method of the        invention, then    -   making the packaging from the film provided with the said scored        line.

Here again, it will be understood that the first layer may possibly bedefined by several sublayers of plastic materials which may bedifferent, for example polypropylene and polyamide.

According to yet another aspect, the invention provides a filmcomprising at least one plastic layer having a scored line, the saidplastic layer forming a bead on its surface along:

-   -   a single side of the scored line, or    -   on each side of the scored line, one of the said beads being        higher than the other of the said beads.

When the said plastic material layer forms a bead on its surface alongeach side of the scored line, it is preferred that one of the said beadsis at least 30%, preferably at least 50%, more advantageously at least100%, higher than the other of the said beads.

The invention also provides a film comprising at least one plasticmaterial layer having a scored line, the said plastic material layerforming a bead on its surface along each side of the scored line, thecross-sectional area of one of the said beads being greater than thecross-sectional area of the other of the said beads. It is preferredthat said cross-sectional area of one of the said beads is at least 30%,preferably at least 50%, more advantageously at least 100%, greater thansaid cross-sectional area of the other of the said beads.

The invention further provides a film comprising at least one plasticmaterial layer having a scored line, the said plastic material layerforming a bead on its surface along each side of the scored line, one ofthe said beads providing a higher mechanical resistance to the saidplastic material layer with respect to the other of the said beads.

The invention furthermore provides a film comprising at least oneplastic layer having a scored line, the said plastic layer forming abead on its surface along on each side of the scored line, one of thesaid beads providing a higher mechanical resistance to the said plasticlayer with respect to the other of the said beads.

Of course, for each of these films, if the scored line is ofdiscontinuous type, the bead of these films may also be discontinuous.

According to yet another aspect, the invention provides a filmcomprising at least one plastic layer in which is made:

-   -   a groove forming a scored line, or possibly    -   a series of perforations where the film comprises at least one        other layer,

the groove or the perforations being produced without removing materialfrom the said layer.

The groove may be of continuous or discontinuous type.

According to yet another aspect, the invention relates to a packaging,which may especially be designed to undergo a preservation treatment inparticular after it has been filled and closed, comprising at least oneflexible wall, the said flexible wall comprising a plastic layer inwhich is made:

-   -   a groove forming a scored line, or possibly    -   a series of perforations where the film comprises at least one        other layer,

the groove or the perforations being produced without removing materialfrom the said layer.

The groove may especially correspond to at least one incision.

According to yet another aspect, the invention relates to a packaging,which may especially be designed to undergo a preservation treatment inparticular after it has been filled and closed, comprising at least oneflexible wall, the said flexible wall comprising a plastic layer inwhich a groove forming a scored line is made, the said plastic layerforming a bead on its surface along:

-   -   a single side of the scored line, or    -   on each side of the scored line, one of the said beads being        higher than the other of the said beads.

When the said plastic material layer forms a bead on its surface alongeach side of the scored line, it is preferred that one of the said beadsis at least 30%, preferably at least 50%, more advantageously at least100%, higher than the other of the said beads.

The bead may be made from material which has plastically flowed out ofthe groove made in the said layer.

Advantageously, a second groove forming a second scored line is made inthe said layer, the second groove extending at some distance along thefirst groove, in which the single bead or the highest bead of each ofthe grooves is arranged along the groove on the side away from the othergroove, the two scored lines preferably being separated by 2 to 5millimeters and the two lines preferably also being parallel.

The invention also provides a packaging, which may especially bedesigned to undergo a preservation treatment in particular after it hasbeen filled and closed, comprising at least one flexible wall, the saidflexible wall comprising a plastic material layer in which a grooveforming a scored line is made, the said plastic material layer forming abead on its surface along each side of the scored line, wherein thecross-sectional area of one of the said beads is greater than thecross-sectional area of the other of the said beads. It is preferredthat said cross-sectional area of one of the said beads is at least 30%,preferably at least 50%, more advantageously at least 100%, greater thansaid cross-sectional area of the other of the said beads.

The bead may be made from material which has plastically flowed out ofthe groove made in the said layer.

Advantageously, a second groove forming a second scored line is made inthe said layer, the second groove extending at some distance along thefirst groove, in which the bead of each of the grooves having thegreatest of said cross-sectional areas is arranged along the groove onthe side away from the other groove, the two scored lines preferablybeing separated by 2 to 5 millimeters and the two lines preferably alsobeing parallel.

Further, the invention also proposes a packaging, comprising at leastone flexible wall, the said flexible wall comprising a plastic layer inwhich a groove forming a scored line is made, the said plastic layerforming a bead on its surface along on each side of the scored line, oneof the said beads providing a higher mechanical resistance to the saidplastic layer with respect to the other of the said beads.

Further, the bead may be made from material which has plastically flowedout of the groove made in the said layer.

Advantageously, a second groove forming a second scored line is made inthe said layer, the second groove extending at some distance along thefirst groove. In this case, the single bead or the highest bead or thebead providing the highest mechanical strength—which ever embodiment isconsidered—of each of the grooves is arranged along the groove on theside away from the other groove. The two scored lines are preferablyseparated by 2 to 5 millimeters. They are advantageously parallel.

For the various packagings according to the invention, if the scoredline is of discontinuous type, the bead(s) may also be discontinuous.

For the various packagings according to the invention, it isadvantageous that the scored line is made in the face of the walltowards the inside of the packaging. Moreover, the wall may comprise alayer made of a light metal such as aluminum. The said plastic layer ispreferably made of polypropylene. Moreover, the packaging may comprise asecond flexible wall, the first and the second wall being joined bytheir side edges and preferably comprising welds on the side edges.

When opening the packaging according to the invention, the tear ispropagated along the scored line thus produced. A directed and cleanopening of the packaging is thus provided.

Within the scope of the present invention, the term “preservationtreatment” refers to any treatment known to a person skilled in the art,in particular heat treatments such as conventional sterilization, flashsterilization and pasteurization.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will becomeapparent on reading the following description of preferred embodimentsof the invention, given by way of example and with reference to theappended drawing.

FIG. 1 is a detailed view of part of a film from which a packagingaccording to the invention can be made.

FIG. 2 is a perspective view of a device according to the invention forproducing scored lines in a film.

FIG. 3 is a front view of the device of FIG. 2, its scoring roller beingseen in longitudinal section.

FIG. 4 is a top view of the scoring roller of the device of FIG. 2.

FIG. 5 is a longitudinal section of the scoring ring intended to bemounted on the scoring roller of the device of FIG. 2.

FIG. 6 is a schematic longitudinal section taken locally at one of theribs of the scoring roller of the device of FIG. 2 when the film ispresent.

FIG. 7 illustrates schematically the path of the film passing throughthe device of FIG. 2.

FIG. 8 is a schematic longitudinal section taken locally at one of theribs of the scoring roller of the device of FIG. 2 according to avariant.

FIG. 9 is a diagram illustrating an improvement of FIG. 3.

FIG. 10 is a schematic perspective view of another device according tothe invention for producing scored lines in a film.

FIG. 11 is a perspective view of a scoring wheel of the device of FIG.10.

FIG. 12 a is an axial section of the scoring wheel of FIG. 10, limitedto the region of the circumferential ribs.

FIG. 12 b is an axial section showing the film placed between thescoring wheel and the sonotrode, FIG. 12 c showing a local enlargementof the rib forming the scoring.

FIGS. 13 a and 13 b respectively show a perspective view of a portion ofthe circumference of the scoring wheel and a radial section of thescoring wheel at a rib, in the case where the ribs of the scoring wheelare made in the form of teeth in order to form discontinuous grooves inthe film.

FIGS. 14 a and 14 b respectively show a perspective view of a portion ofthe circumference of the scoring wheel and a radial section of thescoring wheel at a rib, in the case where the ribs of the scoring wheelare continuous in order to form continuous grooves in the film.

FIG. 15 is a schematic perspective view of a variant of the device ofFIG. 10.

FIGS. 16 and 17 are perspective views of a shoe of the device of FIG.15, FIG. 16 showing an enlargement thereof.

FIGS. 18 a to 18 c each show a cross section of the shoe of FIG. 17taken at three different locations over the length of the shoe.

FIG. 19 shows a vertical section of the device along a rib of the shoe.

FIG. 20 shows a section of the device along the line of section A-Adefined in FIG. 19, FIG. 21 showing a local enlargement of a rib of theshoe.

FIGS. 22 a and 22 b are front and sectional side views respectively of apackaging of the flat bag type.

FIGS. 23 a and 23 b are front and sectional side views respectively ofanother packaging of the flat bag type.

FIGS. 24 a and 24 b show front and sectional side views respectively ofa packaging of the bag type with a gusset.

FIGS. 25 a, 25 b and 25 c show another packaging of the bag type with agusset, respectively seen from the front, in section from the side andseen in three-quarters perspective.

FIGS. 26 a, 26 b and 26 c show a packaging of the bag type with two sidegussets seen from the front, in section along the plane A-A and inschematic three-quarters perspective view, respectively.

FIG. 27 a is a three-quarters perspective view of one embodiment of apackaging according to the invention, in the closed state.

FIG. 27 b is a three-quarters perspective view of the packaging of FIG.8 a, in the half-open state.

FIG. 28 a is a detailed view of a welded edge of the packaging of FIG. 8a.

FIG. 28 b is a detailed view of a welded edge of a variant embodiment ofthe packaging according to the invention.

FIG. 29 is a schematic view of a device for implementing the methodaccording to the invention.

FIG. 30 is a schematic view of another device for implementing themethod according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a film structure typically used for manufacturingpackagings, especially in the form of pouches, intended to containfoodstuffs especially for animals. For this reason, they mustconventionally withstand sterilization in a moist atmosphere and underpressure.

As can be seen in this figure, this film 10 comprises three layers 11,12, 13, that is an upper layer 11 and a lower layer 12 made of plasticand a central layer 13 made of a light metal sandwiched between the saidupper 11 and lower 12 layers. The upper layer 11 forms the outer face ofthe packagings, while the lower layer 12 forms their inner face.

The lower layer 12 may in fact comprise one or more successive layers ofplastics which may differ from each other, each one being able tofulfill a specific function. The same applies for the upper layer 11.

In the example illustrated in FIG. 1, the upper layer 11 forming theouter face of the packaging is made of polyethylene terephthalate, thecentral layer 13 is made of aluminum and the lower layer 12 forming theinner face of the packaging comprises successively a layer 12 a ofpolyamide—preferably oriented polyamide—and a layer 12 b ofpolypropylene.

The polyethylene terephthalate layer defining the outer face of thepackaging serves as a printing medium and makes it possible to providethe packaging thus produced with its external appearance, for example agloss or matt appearance.

The central layer 13 made of aluminum forms a barrier to external gas,especially oxygen and water vapour, in order to isolate in an efficientmanner the foodstuff contained in the packaging.

The first layer 12 a of the lower layer 12 of the film 10 is in thiscase made of polyamide which makes it possible for the packaging to bemechanically strengthened and to prevent perforations from the outside.The second layer 12 b, made of polypropylene, acts as a welding agent toallow the edges of the packaging to be welded. The polypropylene alsoendows some mechanical strength to the packaging and ensures goodsealing of the welds.

As a variant, provision may be made for the upper layer 11 of the filmforming the outer face of the walls of the packaging to comprise asuccession of two layers, an outer polyethylene terephthalate layer andan inner polyamide layer, the central layer 13 still being made ofaluminum. In this case, the lower layer 12 forming the inner face of thewalls of the said packaging is preferably made only of polypropylene.

According to another variant, the outer layer 11 of the film forming theouter face of the packaging is made only of polyethylene terephthalate,the central layer 13 of aluminum and the lower layer 12 of the filmforming the inner face of the packaging is made only of polypropylene.

In general, the polyethylene terephthalate layer has a thickness ofbetween about 10 and 20 μm, the polyamide layer has a thickness also ofbetween 10 and 20 μm, the central aluminum layer has a thickness betweenabout 7 and 12 μm and the polypropylene layer has a thickness of between30 and 100 μm.

Conventionally, between each layer of the said film 10, an adhesivecoating layer is provided to allow the said layers forming it to besecured together by virtue of a lamination operation.

Furthermore, provision can also be made for the inner face of thepolyethylene terephthalate layer to be printed. Of course, markings canalso be made on its outer face, which is generally the case after makingthe pouch in order to affix thereon for example a use-by date.

The invention relates in particular to the manufacture of a packagingfrom one or more film(s) especially of the type described in relation toFIG. 1.

For the following description of the invention, reference will be madeto the aforementioned film 10 having an outer layer 11—forming the outerface of the packaging—made only of polyethylene terephthalate, a centrallayer 13 made of aluminum, and a lower layer 12—forming the inner faceof the packaging—made only of polypropylene. But, of course, theinvention can be implemented with any structure for the film previouslydescribed. More generally it is applicable to any film having at leastone plastic layer.

According to the invention, the scored line or lines are preferably madein the film prior to the operations of making the packaging from thisfilm. The operations of making the packaging from this film are knownper se.

FIGS. 2 to 5 illustrate a device according to the invention making itpossible to produce at least one scored line in a film.

The device comprises a cylindrical reference roller 21 and a scoringroller 22 which is also cylindrical. The axes of the rollers 21 and 22are parallel.

The rollers 21 and 22 are mounted so that they can rotate, for example,between two lateral uprights 23 a, 23 b of a frame 20. Beams 24 a, 24 bmay connect the upper parts of the uprights 23 a, 23 b in order tostiffen the assembly.

During the scoring operation, the film 10 passes between the two rollers21 and 22.

The reference roller 21 acts as a bearing surface for the film 10. Morespecifically, it is the upper layer 11 of the film 10 which bears on theroller 21.

The scoring roller 22 has four ribs 26 a, 26 b arranged on itscircumference. They are not shown in FIG. 3 for the sake of clarity ofthis figure. These ribs 26 a, 26 b therefore form projections on thecircumferential surface of the roller 22. Each rib is located in arespective radial plane about the roller 22.

Each of the ribs 26 a, 26 b is provided to cut into the lower layer 12of the film 10—that is to say the layer forming the inner face of thewalls of the pouch—in order to form thereon a corresponding groove asthe film 10 travels between the rollers 21 and 22. Each groove has theeffect of weakening the film 10 at this location and therefore forms ascored line.

The ribs 26 a, 26 b preferably have a cutting profile capable ofincising the lower layer 12 of the film 10, without removing material.Thus, the ribs 26 a, 26 b may have a pointed triangular cross section asillustrated in FIG. 4. The cross section of each rib 26 a, 26 b ispreferably identical around the entire circumference of the roller 22.Furthermore, all the ribs 26 a, 26 b preferably have the same crosssection and the same dimensions.

FIG. 6 shows a longitudinal section taken locally in the region betweenthe scoring roller 22 and the reference roller 21 at one of the ribs 26a. As indicated, the film 10 rests on the reference roller 21 while therib 26 a has penetrated into the lower layer 12. The rib 26 a onlypenetrates into part of the thickness of the lower layer 12 of the film10, but does not perforate this layer. Thus the rib 26 a does not damagethe aluminum layer 13 given the fragility thereof, and therefore it willcarry out its function of sealing the pouch correctly. Of course, thisdescription is also valid for the other ribs 26 a, 26 b which are notshown in FIG. 6.

In operation, the reference roller 21 is preferably rotated in order tohave a tangential speed equal to the run speed of the film between therollers 21 and 22. Thus, there will be no friction between the film 10and the roller 21. Similarly, it is advantageous for the roller 22 alsoto be rotated so that the ribs 26 a, 26 b have a tangential speed equalto the run speed of the film between the rollers 21 and 22. Thus, therewill be no or very little friction between the side walls of the ribs 26a, 26 b and the walls of the groove which they form in the lower layer12 of the film 10. For this, it is possible to provide a drive shaft 25in order to rotate one of the rollers and gearing 27 a, 27 b in orderalso to transmit the rotation to the other roller. As a variant, it ispossible for the reference roller 21 to be mounted free to rotate, inwhich case it is the film 10 which will rotate it. The same may holdtrue for the scoring roller 22.

In practice, it is advantageous that the ribs 26 a, 26 b are notarranged directly on the surface of the roller 22, but rather on a ring27 which is mounted on the roller 22. In this way, it is easy to changethe number of scored lines, their shape and/or their depth by replacingonly the ring 27, instead of the complete roller 22.

Given the small thickness of the lower layer 12 of the film 10, thedevice is designed to give accurate positioning of the ribs 26 a, 26 bwith respect to the surface of the reference roller 21 at least when itis important that this layer is not perforated to prevent damaging thecentral aluminum layer 13. To this end, the roller 22 may be embodied asfollows.

The roller 22 has a running track 28 a, 28 b at each end, which bears ona corresponding surface of the reference roller 21. This contacttherefore makes it possible to position the scoring roller 22 accuratelywith respect to the reference roller 21. To provide good contact of therunning tracks 28 a, 28 b on the roller 21, provision is made to tensionthe rollers 21 and 22 one against the other. This can be obtained, forexample, by means of press rollers 29 a, 29 b bearing on the runningtracks 28 a, 28 b on the side away from the reference roller 21. In thiscase, the scoring roller 22 is mounted so that it can rotate on thelateral uprights 23 a, 23 b via bearings 30 a, 30 b—for example ballbearings or the like—which advantageously slide vertically in theuprights 23 a, 23 b. For this purpose, the bearings 30 a, 30 b may, forexample, be guided by a vertical slot made in the lateral uprights 23 a,23 b. In contrast, the reference roller 21 is mounted so that it canrotate on the lateral uprights 23 a, 23 b by means of bearings 31 a, 31b—for example ball bearings or the like—which are fixed with respect tothe structure 20 at least in operation. For this purpose, the bearings31 a, 3 b may simply come to a stop at the bottom of the aforementionedvertical slot made in the uprights 23 a, 23 b. The press rollers 29 a,29 b may be mounted on a beam 32 which slides with respect to theuprights 23 a, 23 b. Screws 34 a, 34 b screwed through a fixed beam 33,connecting the lateral uprights 23 a, 23 b, exert pressure on thesliding beam 32, and consequently the press rollers 29 a, 29 b press thescoring roller 22 onto the reference roller 21. It is advantageous toprovide a force sensor in order to measure the force exerted by thescoring roller 22 on the reference roller 21 so that this force can beset to a desired value. This force sensor may comprise two piezoelectricsensors on which the bearings 31 a, 31 b of the reference roller 21 restat the bottom of the guiding slot of the lateral uprights 23 a, 23 b.Given that the bearings 31 a, 31 b of the reference roller 21 are fixedin this example, it is preferably the reference roller 21 which isdirectly driven by the drive shaft 25, the gearing 27 a, 27 btransmitting the rotation to the scoring roller 22. Of course, theassembly described to tension the rollers 21 and 22 one against theother can be reversed with respect to the rollers 21 and 22.

The running tracks 28 a, 28 b are preferably attached to the roller 22.For this purpose, they can be mounted with adjustment on the end of theroller 22. It is preferable to resort to accurate adjustment, forexample uncertain adjustment of the H7g6 type.

In order to be able to position the ribs 26 a, 26 b accurately withrespect to the reference roller 21, it is advantageous to accommodatethe radial clearances. There is in fact a radial clearance between therunning tracks 28 a, 28 b and, if appropriate, also between the scoringring 27 and the roller 22. This is because, in order to facilitatemounting of the ring 27 on the roller 22, it is advantageous to providea clearance between them. These radial clearances can be accommodated byexpanding of the scoring roller 22.

To this end, the roller 22 may be made in the form of a hollow tube. Theroller 22 is borne by a shaft 35 by means of the running tracks 28 a, 28b each one made in the form of an end plate and attached to the ends ofthe roller 22 by adjustment, as already indicated. Furthermore, theshaft 35 bears the gearwheel 27 a of the gearing transmitting therotation from the roller 21 to the roller 22. The end plates forming therunning tracks 28 a, 28 b are mounted on the shaft 35 and preferablyadjusted to fit closely. As such, there is no additional radialclearance at this level. Furthermore, the end plates forming runningtracks 28 a, 28 b may be secured to the shaft 35 by means of one or moreradial pins.

Preferably, the roller 22 is mounted without axial clearance, forexample, by virtue of a shoulder of the shaft 35 against which the endplate 28 a presses and a nut pressing against the other end plate 28 b.The reference roller 21 is preferably also mounted on the structurewithout axial clearance.

A heating element 36 is placed inside the roller 22. Advantageously,this is one or more hollow cylindrical mica-insulated heating resistors.To ensure good transmission of heat to the roller 22, the resistor orresistors are preferably pressed against its inner wall. Advantageously,the resistor or resistors are split and an expandable collar (not shown)placed inside the resistor or resistors press the latter against theinner wall of the roller 22.

The heating of the roller 36 can be set to completely adjust the radialclearances. It may advantageously be adjusted to cause a tight fitbetween the ring 27 and the roller 22 and preferably also between theend plates 28 a, 28 b and the roller 22.

Of course, a person skilled in the art will choose the materials for theparts depending on their expansion coefficient and will determine thedimensions of the parts and the cold adjustments to obtain the desiredclearance with respect to the temperature reached when hot.

The temperature to which the roller 22 is brought is preferably lessthan the melting point of the lower layer 12 of the film 10, in thiscase 160° C. The temperature to which the outer surface of the roller 22is brought may advantageously be chosen within the range from 80 to 130°C.

Moreover, it is preferable that only the ribs 26 a, 26 b come intocontact with the film 10, but not the rest of the surface of the ring 27or of the roller 22, which is hot, in order to prevent possiblesoftening of the lower layer, 12 of the film 10.

It is advantageous to provide temperature control for the roller 22using, for example, a power controller in order to supply the heatingresistors. To this end, a temperature probe can be installed inside theroller 22 in order to measure the temperature thereof. Preferably, it isdirectly, fastened to the inner wall of the roller 22.

To supply the heating resistors 36 with electricity and to connect thetemperature probe, a brush commutator 37 is provided at the end of theshaft 35, on the outside of one of the lateral uprights 23 a, 23 b. Theelectrical wires connecting the resistors 36 and the temperature probemay emerge from the roller 22 through an opening 28 made in the endplate 28 a which is on the same side as the commutator. The wires maythen pass inside the shaft 35 through an opening 39 to come againsttracks arranged at the end of the shaft and which cooperate with thebrushes of the commutator 37.

Preferably, the reference roller 21 is not heated. If appropriate, itmay be cooled for example by ventilation. As such, there is no expansionof the reference roller 21 affecting the positioning of the film 10 withrespect to the ribs 26 a, 26 b. Of course, the diameter of the referenceroller 21 is determined according to the width of the film 10 in orderto be sufficiently stiff.

To ensure the film 10 is properly placed on the reference roller 21, itis preferable that the running track of the film 10 makes an angle withthe reference roller 21, as illustrated schematically in FIG. 7. FIG. 7shows, by way of example, a first reel 3 from which the film 10 isunwound and a second reel 3 onto which the film 10 is wound after thescored lines are produced by the scoring roller 22.

The scored lines may be continuous in the film 10, that is to say thateach scored line corresponds to an uninterrupted groove made in thelower layer 12. For this, the ribs 26 a, 26 b are continuous over theentire circumference of the ring 27 of the roller 22.

The scored lines may also be discontinuous in the film 10, that is tosay that each scored line corresponds to a successive series ofincisions produced in the lower layer 12. For this, each rib 26 a, 26 bis discontinuous over the circumference of the ring 27 of the roller 22so as to form thereon a series of successive teeth. Preferably, theteeth are all identical to each other and two successive teeth arealways separated by an identical space. For example, the teeth may havea length of 0.3 mm and a space between two successive teeth of 0.2 mm.These dimensions may also be greater, for example a tooth length of 2 mmand a spacing of 0.8 mm.

Provided the scored lines do not pass through the lower layer 12 of thefilm 10, they may optionally extend into the edge regions which will bewelded together in order to make the pouch. In other words, they thenextend over the entire width of the pouch. However, it is also possiblenot to continue the scored lines into the welding regions. For this, itis enough to remove the ribs at the corresponding portion of the ring 27of the roller 22.

By way of example, the reference roller 21 can be made from treated andground steel, as can the running tracks 28 a, 28 b. The hollow roller 22may advantageously be made from aluminum because of its expansioncoefficient. Its external diameter may be between 150 and 250 mm and thethickness of the wall between 10 and 30 mm. The scoring ring 27 may bemade from steel, a steel alloy or brass. The diameter of the referenceroller may be between 100 and 300 mm for widths of film 10 of about 500to 700 mm. The scoring ring 27 may have a thickness of about 3 mm and ispreferably polished. The ribs 26 a, 26 b preferably have a height ofbetween 0.5 and 1 mm. The cold clearance between the ring 27 and theroller 22 may be between 0.1 and 0.4 mm. The power of the heatingresistors may be between 1 500 and 3 000 W.

Moreover, it will be noted that the roller 22 can easily be interchangedby virtue of its sliding bearings 30 a, 30 b, which makes it possible,for example, for another roller 22 of different diameter to be mountedquickly.

In practice, the depth of the groove may be between 50 and 60 μm for alower layer 12 of 70 μm thickness.

Of course, the number of scored lines may be varied by changing thenumber of ribs on the ring 27.

Where the scored line is discontinuous, the teeth forming the ribs 26 a,26 b may take the shape of needles instead of being elongated.

Moreover, it is perfectly possible to use the device to produce groovesin the lower layer 12 before the latter is assembled to the other layersforming the film 10, that is to say before the operation of laminatingthe film 10. If it is acceptable, for making the packaging and itsfunctionalities, for the lower layer 12 to have scored lines formed bysuccessive perforations, each rib 26 a, 26 b may be in the form of teethwhich are long enough to perforate the lower layer 12. For each rib 26a, 26 b, it is possible to provide—a corresponding circumferential slot21 a made in the surface of the reference roller 21. Thus, the teethwill penetrate the slot as illustrated in FIG. 8. With this use of thedevice, it is not useful to provide adjustment for the radial clearancesas described above.

An improvement to the device consists in providing adjustment for thedistance between the axes of the reference roller 21 and of the scoringroller 22. Thus, it is possible to vary the depth of the grooves or elseto adapt the device to films having different thicknesses. For this, therunning tracks 28 a, 28 b and the corresponding bearing regions of thereference roller 21 may be slightly conical. By axially offsetting theconical surfaces of one of the rollers with respect to those of theother roller, the distance between the axes is varied. For example, asillustrated schematically in FIG. 9 for the running track 28 a, the endplates forming running tracks 28 a, 28 b are conical and arrangedfastened to the roller 22. In contrast, end plates—referenced 28a′—having a corresponding outer rolling surface can be mounted on theshaft of the reference roller 21 so that they can be displaced in theaxial direction by means, for example, of screws. Thus it is possible tovary the depth of the grooves, for example, over an interval of 50 μm,or even more, by relative axial displacement of a few millimeters.

We will now describe another device according to the invention forproducing at least one scored line in a film. To form the scored lines,this device is based on a tool having projections in order to penetratethe lower layer 12 of the film 10 and cause plastic flow of the materialof the layer 12 in combination, for example, with ultrasound.

In the embodiment shown in FIG. 10, the device comprises two cylindricalscoring wheels 51 a, 51 b arranged coaxially and mounted so as to rotatepreferably on the same shaft (not shown). Each of the scoring wheels 51a, 51 b has two ribs 52 a, 52 b arranged on its circumference. Theseribs 52 a, 52 b project from the circumferential surface of thecorresponding scoring wheel. In the example illustrated, each rib 52 a,52 b is located in a respective radial plane on the correspondingscoring wheel 51 a, 51 b.

In operation, the film 10 runs between the scoring wheels 51 a, 51 b onthe one hand and a sonotrode 50 on the other. More specifically, thelower layer 12—that is to say the one forming the inner face of thepackaging—is on the same side as the scoring wheels 51 a, 51 b and theupper layer 11 is on the same side as the sonotrode 50. The film 10 ispressed between the scoring wheels 51 a, 51 b and the sonotrode 50. Thesonotrode, 50 vibrates at ultrasound frequencies to allow the plasticflow of the material of the layer 12. The scoring wheels 51 a, 51 b actas an anvil for the sonotrode. The result of this is that the ribs 52 a,52 b penetrate the lower layer 12 of the film 10, the penetration beingaccompanied by the plastic flow of the material of the layer 12 towardsthe outside of the groove thus formed by each rib.

The plastic flow of the material towards the outside of the groove maytake place either along a single edge of the groove, or along both edgesdepending on the shape of the cross section of the ribs 52 a, 52 b. Thisresults in the formation of a bead along one of the edges of the grooveor the formation of a respective bead on each side of the groove. Thesebeads have the advantage of increasing the strength of the film 10around the groove, which improves the guiding when opening the packagingalong the scored line thus formed. In a preferred manner, the film 10runs tangentially to the circumference of the scoring wheels 51 a, 51 balong the working surface 50 a of the sonotrode 50. The ultrasonicvibrating movement of the sonotrode 50 takes place in the direction ofthe scoring wheels 51 a, 51 b. In fact, it is advantageous for the planeof the sonotrode 50 to comprise the axis of the scoring wheels 51 a, 51b.

Each scoring wheel 51 a, 51 b has at least one circumferential bearingsurface on which the film 10 bears when it runs between the scoringwheels and the sonotrode 50. The ribs 51 a, 51 b project from thisbearing surface. The height A of the ribs 51 a, 51 b above the bearingsurface determines the depth of the grooves formed in the lower layer 12of the film 10. Moreover, in order to allow the plastic flow of thematerial of the layer 12 towards the outside of the groove in order toform one or two beads along the latter, the scoring wheel is providedwith a corresponding circumferential recess along the ribs 52 a, 52 b

FIGS. 11 and 12 a-c illustrate a preferred rotary-cutter configurationprovided to make the material of the lower layer 12 of the film 10plastically flow towards just one single side of each of the groovesformed. In particular, FIG. 12 a shows the axial cross section of thescoring wheel 51 a at the ribs 52 a. FIG. 12 b shows, in axial crosssection, the film 10 taken between the sonotrode 50 and the scoringwheel 51 a and FIG. 12 c shows a local enlargement of the rib on theright-hand side of the scoring wheel 51 a. The circumferential bearingsurface on which the film 10 bears when it runs between this scoringwheel and the sonotrode 50 is referenced 53. So that the materialplastically flows only towards one edge of the groove, the cross sectionof the ribs 52 a is asymmetric. In this case, the profile of the rib hasa wall which is inclined with, respect to the bearing surface 53, inorder that the rib becomes gradually thinner towards its apex. Thematerial of the lower layer 12 plastically flows along this inclinedwall towards the outside of the groove formed by this rib. In contrast,the opposite wall of the profile of the rib is at right angles withrespect to the bearing surface 53, or even possibly has a negativetaper. Hence, the material of the lower layer 12 does not flowplastically towards the outside along this right-hand wall. The width ofthe rib obviously determines the width of the resulting groove in thelayer 12 of the film 10. By way of example, the width at the apex of theprofile of the rib may be chosen from the interval ranging from 0.1 to0.2 mm. The angle of the inclined wall of the rib with respect to thebearing surface 53 may advantageously be chosen from the intervalranging from 55 to 80°. The height of the rib may be chosen so as toleave only 10 μm of material of the layer 12 under the groove. Thus, fora layer 12 of 70 μm thickness, it is possible to adopt a rib height A of60 μm. Such dimensioning makes it possible to ensure the integrity ofthe aluminum central layer 13.

By way of example, the vibration frequency of the sonotrode is between20 and 70 kHz. Advantageously, it is 40 kHz in the case of thepolypropylene layer 12. The amplitude of the ultrasound vibrations ispreferably at least 5 μm, but more advantageously at least 20 μm. Anamplitude of 25 μm is particularly preferred. Moreover, the diameter ofthe scoring wheel at the bearing surface 53 is preferably greater than60 mm. Each scoring wheel 51 a, 51 b exerts a compressive force on thefilm 10 against the sonotrode 50, which is advantageously within theinterval ranging from 1.5 to 2.5 daN. This compression is preferablyexerted by pushing the shaft of the scoring wheels towards thesonotrode, it being possible for the shaft to be mounted on a structureby means of sliding bearings on which the required force is exerted.

In the example illustrated, for each groove formed by the correspondingrib 52 a, the plastic flow of the material takes place along the grooveon the side away from the other groove formed by the other rib 52 a ofthis same scoring wheel. The bearing surface 53 extends between the tworibs 52 a, 52 b. It is therefore the height A of the ribs 52 a, 52 b,measured from the bearing surface 53, which determines the depth of thegrooves formed in the lower layer 12 of the film 10. There is no recessin the bearing surface 53 along the ribs 52 a since there is no plasticflow outward on this side of the ribs. The circumferential surfaces 54 aand 54 b extending outwards from the ribs 52 a are located at a levellower than that of the bearing surface 53. In other words, the height Bof the ribs 52 a measured from the circumferential surfaces 54 a, 54 bis greater than the aforementioned height A. Here, this difference inlevel forms the aforementioned recess allowing the formation of beadsalong the grooves formed in the layer 12 of the film 10, as illustratedin FIG. 12 c in which the bead formed is referenced 55.

Of course, it is possible for the material of the layer 12 to flowplastically outward from the other side of a groove by reversing theaforementioned profile, that is to say by arranging the inclined wall ofthe rib 52 a in question on the side towards the other rib 52 a. In thiscase, a recess can be made in the bearing surface 53 along the rib inquestion so as to allow the formation of the bead. It is also possibleto use the surfaces 54 a and 54 b as bearing surface and to reduce thelevel of the surface 53 with respect to the surfaces 54 a and 54 b so asto define the desired recess.

Of course, if it is desired that the material of the layer 12 flowsplastically on either side of the groove, the profile of the rib 52 a inquestion just has to be modified by replacing the right-hand wall with awall inclined in a similar manner to the opposite wall. In this case, arecess is preferably provided on the scoring wheel along each side ofthe rib in question. If rib 52 a has a symmetrical cross-section, itflows plastically the same amount of material towards each side of thegroove and results in forming a bead 55 along each side of the groovehaving the same shape, dimensions and cross-sectional area. Thus, themechanical strength of the plastic material layer is increased alongeach side of the groove to a same extent. On the contrary, if rib 52 ais given an asymmetrical cross-section, the proportion of materialflowed towards each side of the groove is different and results informing a bead 55 along each side of the groove having—with respect tothe other bead—different dimensions, in particular a different heightand cross-sectional area, and possibly a different shape too. Thus, themechanical strength of the plastic material layer is increased alongeach side of the groove to a different extent. The highest bead orhaving the most important cross-sectional area provides the mostimportant increase of mechanical strength to the plastic material layer.As already mentioned, the asymmetrical cross-section can be designed sothat the material is flowed plastically outward only towards one side ofthe groove.

Moreover, it is preferable that the active part of the sonotrode 50 islong enough to cover the whole active circumferential portion of thescoring wheel as shown in FIGS. 13 b and 14 b. The scoring wheels may beproduced by machining from steel which may have received a surfacetreatment.

By virtue of this device, it is equally possible to form grooves of thecontinuous or discontinuous type. To form a continuous groove, the ribsjust have to be continuous over the circumference of the scoring wheelas illustrated in FIGS. 14 a-b. To form a discontinuous groove, the rib52 a in question just has to be interrupted at different locations ofthe circumference of the scoring wheel 51 a. In other words, the rib ismade in the form of a series of teeth over the circumference of thescoring wheel 51 a. FIGS. 13 a-b give an example thereof. It ispreferable that the teeth all have the same length and that each of themis separated from the next by the same space in order to attain a scoredline having the same preweakening over, its entire length. By way ofexample, the length of a tooth may be chosen from the interval rangingfrom 0.2 mm to 0.4 mm and a space between two teeth chosen from theinterval ranging from 0.1 to 0.3 mm.

In general, the rib preferably always has the same cross section and thesame size over its entire length.

Moreover, provided the continuous scored lines do not pass through thelower layer 12 of the film 10, they may optionally extend into the edgeregions which will be welded together to make the pouch. In other words,they then extend over the entire width of the pouch. However, it is alsopossible not to continue the scored lines into the welding regions. Forthis, the ribs just have to be removed over the corresponding portion ofthe rotary wheel 51 a.

The rotary wheels 52 a, 52 b can be mounted so that they are free torotate. They may also be driven in rotation with a tangential speed attheir bearing surface 53 which is equal to the run speed of the film 10.

Of course, the description of the scoring wheel 51 a is also applicableto the scoring wheel 51 b. Moreover, the scoring wheel 51 b ispreferably identical to the scoring wheel 51 a, each one producing inour example two scored lines in a corresponding wall of the packagingsubsequently made.

Instead of having two scoring wheels 51 a, 51 b, it is possible to useonly a single wider scoring wheel on which the four ribs 52 a, 52 b arearranged. Nevertheless, it is advantageous to use two separate scoringwheels in order to be able to adjust their axial spacing, for example,by virtue of spacers of different length,

Of course, the number of scored lines can be freely chosen by supplyinga corresponding number of ribs.

FIGS. 15 to 21 illustrate another embodiment of the ultrasound deviceaccording to the invention in which the scoring wheels 51 a, 51 b arereplaced by two shoes 71 a, 71 b. Thus the film 10 is pressed betweenthe sonotrode 50, on the one hand, and the shoes 71 a, 71 b, on theother. This embodiment of the invention makes it possible to producecontinuous grooves with excellent control of the plastic flow of thematerial.

Each of the shoes corresponds overall to the arrangement of thecircumference of the scoring wheels 51 a, 51 b of FIG. 10, but in adeveloped form. For this reason, the description given of this subjectrelating to the scoring wheel of FIG. 10 is applicable mutatis mutandis.However, the configuration with shoes may have beneficial specificfeatures which we will see.

We will describe the shoe 71 a with reference to FIGS. 15 to 21, thisdescription being valid also for the other shoe 71 b. The arrow Fdenotes the run direction of the film. The shoe 71 a has two parallelstraight ribs 72 a and a bearing surface 73 extending between these tworibs. In operation, the running film 10 bears on the surface 73. Theribs 72 a project from the bearing surface 73. The maximum height of theribs 72 a with respect to the bearing surface 73 defines the depth ofthe groove formed in the lower layer 12 of the film 10.

The surfaces 74 a, 74 b are located at a level lower than the bearingsurface 53 in order to allow the material of the layer 12 to flowplastically outwards from the groove along which a bead 75 is thereforeformed. The profile of the ribs is similar to those 52 a, 52 b of FIG.10.

Of course, it is possible for the material of the layer 12 to flowplastically outwards from the groove, that is from one side of thegroove, or from the other, or from both depending on the profile chosenfor the rib in question. A corresponding recess is then arranged alongthe walls of the rib serving to make the material flow plasticallyoutwards from the groove formed. Similarly to the embodiment of FIG. 10,ribs 72 a may have a symmetric or an asymmetric cross-section dependingon the amount of material to be flowed plastically towards each side ofthe groove.

Moreover, it is preferable that the active part of the sonotrode 50 islong enough to cover the entire active part of the ribs, as shown inFIG. 19.

It is advantageous to provide on the shoe a surface 73 a forming a rampupstream of the start of the ribs 72 a and which gradually reaches thelevel of the bearing surface 73. Thus the film 10 arrives on the shoewithout encountering a sharp edge capable of damaging the film. In theexample illustrated, the ramp starts at the surfaces 74 a, 74 b.

The upstream and downstream directions are of course defined accordingto the run direction of the film 10.

It is advantageous that provision is made for the ribs 72 a to graduallyincrease in height from the upstream side of the shoe towards thedownstream side. Similarly, it is advantageous that provision, is madefor the ribs 72 a to gradually broaden from the upstream side of theshoe towards the downstream side. The broadening preferably takes placetowards the side of the inclined wall of the rib, that is to say towardsthe side towards which the rib makes the material flow plastically. Theoverall shape of the cross section of the rib preferably remainsidentical over its entire length. FIGS. 18 a-c illustrate this gradualchange. FIG. 18 a shows a cross section at the start of the ribs 72 awhere they are coincident with the bearing surface 73. FIG. 18 b shows across section taken half-way along the ribs 72 a. FIG. 18 c shows thecross section taken at the apex of the ribs 72 a. By way of example, thewidth of a rib 72 a changes linearly from 0 to 150 μm and its heightchanges linearly from 0 to 60 μm, the length of the rib being 12 mm.Because of this gradual change, the plastic flow of the material of thelayer 12 of the film 10 is gradual and controlled. In particular, itmakes it possible to ensure a plastic flow outwards from the groovetowards only one edge thereof. The strengthening line along the grooveis all the stronger and therefore efficiently prevents the tear alongthe scored line moving away from the latter on the side of this beadduring opening of the packaging by the user. It also allows very widegrooves to be made by virtue of the length of the ribs, which may begreat. The length L of the rib 72 a (not including the part 72 a′described below)—which penetrates the layer 12—is preferably between 5and 75 mm for ultrasound at 40 kHz, and more particularly between 8 and20 mm in the case of polypropylene: in the example shown in FIG. 19, thelength L is 12 mm. For lower ultrasound frequencies, the rib may be evenlonger.

Moreover, it is also advantageous that the height of the ribs 72 adecreases gradually from the highest point of their apex in thedownstream direction. This portion is referenced 72 a′. This allows agradual release of the ribs out of the groove while providing propershaping of the walls of the groove.

Finally, it is advantageous that the profile of the rib has an apex 76forming an edge parallel to the bearing surface 73. This has the effectof giving a flat groove bottom, but may also make it possible to releasethe rib from the layer 12 by switching off the ultrasound. This isbecause, when the plastic flow stops, the rib automatically rises againtowards the surface of the layer 12 over which it slides withoutdamaging it, because of the flat bearing surface defined by the apex 76of the rib. Thus it is possible to break the scored line, for example,in the regions subsequently serving for welding the edges of thepackaging.

The film 10 is preferably compressed by pressure from the shoes towardsthe sonotrode 50. In this case too, the force exerted by each shoe onthe film is advantageously in the interval ranging from 1.5 to 2.5 daN.

Here again, the number of ribs per shoe and the number of shoes may bevaried in consideration of the number of scored lines to be formed.

The shoes may be produced by machining from steel which may havereceived a surface treatment.

The ultrasound devices described are advantageous because the ribsforming a projection are made on the anvil—that is to say the scoringwheels or the shoes in the examples described—and not on the sonotrode.As a result, it is possible to give very variable shapes and dimensionsto the projections serving to form the scored line since they are notsubject to ultrasound, while the active surface of the sonotrode 50 cansimply be flat and therefore particularly suitable for ultrasoundvibrations. In contrast, if the projections were formed on thesonotrode, the shapes and dimensions would be limited because of thestresses induced by the ultrasound vibrations. Moreover, these devicesmake it possible to operate at high film run rates, up to 200 m/min, oreven more.

The devices of the invention are particularly advantageous because theymake it possible to use a cut and/or plastic flow preventing materialbeing removed from the layer 12 during formation of the scored line.Thus, there is no risk of contaminating the food content of thepackaging. Nor is there any burning of the layer 12 of the film 10, norsmoke nor spraying of particles of material from this layer at least inthe case of plastic flow with ultrasound. Furthermore, the film is lessweakened at the scored line than in the case of laser technologies whichinvolves exceeding the melting point of the material of the layer inquestion of the film, which locally alters the structure of the materialand thus makes the layer more resilient. This drawback does not existwhen using a cut and/or plastic flow by ultrasound since the meltingpoint is not exceeded.

Moreover, the continuous scored lines are preferable to thediscontinuous scored lines since the former provide better guiding whenthe packaging is opened by the user. This is because, in the case of thelatter, guiding of the opening is not provided reliably between twosuccessive notches or holes. In the case of discontinuous scored lines,it is preferable to have elongated and aligned notches rather thanhaving round holes obtained, for example, with needles. This is becausethe elongated notches promote guiding of opening along the scored line,unlike round holes.

It is advantageous that the scored lines are not produced by completeperforation of the lower layer 12 in the case of the films 10 taken asan example, particularly in the case of continuous scored lines. Wherethe scored lines pass through the edge regions subjected to welding whenthe packaging is made, the welding remains possible at the groove of thescored line. Welding would not be possible in the case where the grooveforming the scored line passes through the entire layer 12 and thiswould result in a fault in sealing the packaging. Moreover, the part ofthe layer 12 remaining under the groove which does not pass throughprotects the weaker layer 13 especially against accidental folding ofthe packaging along the scored line.

In general, the devices of FIGS. 10 to 21 are more advantageous thanthat of FIG. 2 if they operate on multilayer films, since the referencesurface for positioning the film with respect to the projection bears onthe layer 12, that is to say the layer in which the scored line isproduced. Therefore, the depth of the continuous or discontinuous grooveis better controlled since the tolerances on the other film layers arenot involved. The device of FIG. 2, may be more advantageous where thedevice operates on a single-layer film—for example before lamination—ifit is desired to control the thickness of material remaining under thegroove better.

FIGS. 22 a to 26 c illustrate various examples of packagings which canbe produced from films bearing scored lines produced according to theinvention.

In FIGS. 22 a and 22 b, a packaging 100 is shown which is in the form ofa pouch or bag hermetically sealed by welding. This packaging 100 is aflat bag, that is to say that it comprises two walls welded together onthe four sides 110, 120, 130, 140.

In FIGS. 23 a and 23 b, another packaging 200 of the flat pouch type isshown, which comprises two walls welded only on three sides 210, 220,230 out of four. It has a bottom 250 which is not welded, as shown moreparticularly in FIG. 23 b. In other words, the pouch is made from asheet folded in two, the folded region defining the bottom 250.

In FIGS. 24 a, 24 b, 25 a, 25 b, 25 c and 26 a, 26 b, 26 c, packagings300, 400, 500 of the pouches with gussets type are shown.

More particularly, FIGS. 24 a and 24 b show a packaging 300 comprisingthree welded sides 310, 320, 330 and a bottom 350 comprising a gussetmade by folding.

FIGS. 25 a, 25 b and 25 c show another type of pouch with gussetcomprising three welded sides 410, 420, 430 and a bottom 450 with agusset made with two welded parallel edges.

FIGS. 26 a, 26 b, 26 c show a packaging 500 which comprises two sideedges 510, 530 welded so as to produce on each of the edges 510, 530 agusset, as is more particularly shown in FIGS. 26 b and 26 c.

The packagings 100, 200, 300, 400 and 500 shown respectively in FIGS. 22a to 26 c may especially be designed to be sterilized after they havebeen filled and closed. In general, these packagings in the form of abag or pouch are designed to contain foodstuffs, for example foodstuffsfor animals. Thus, they are produced from materials which must withstandsterilization in a moist atmosphere and under pressure like those givenas an example in relation to FIG. 1.

Of course, types of packagings other than those 100, 200, 300, 400 and500 illustrated can be produced by applying the invention.

FIGS. 27 a and 27 b more particularly show a packaging according to theinvention of the bag type with a gusset shown in FIGS. 25 a, 25 b and 25c, with three welded sides and a gusset formed in its bottom. As shownin FIG. 27 a, this packaging 400 comprises, in its top part, on eachinner face of its walls, two closely spaced parallel scored lines 432,433. They may be produced with a device according to the invention inthe lower layer of the film from which the packaging is manufactured.The space between the two parallel scored lines is between about 2 and 5mm.

In the embodiment shown, each inner face of the walls of the packaging400 comprises the two scored lines 432, 433, but it is also possible tomake provision for a single inner face to have the two parallel scoredlines.

According to one embodiment, the scored line extends over the entirewidth of the film, that is to say the entire width of the packaging asis shown more particularly in FIG. 27 a and in detail in FIG. 28 a.Thus, as shown in these figures, the scored lines extend over the weldededges 430, 410 of the said packaging 400.

According to a variant more particularly shown in FIG. 27 b, provisioncan be made to produce each scored line only on part of the width of thefilm, that is to say part of the width of the packaging, leaving the twolongitudinal edges 430 of the film, intended to be welded to make thesaid packaging, free of grooves or holes. Thus, as is shown in FIG. 28a, each scored line extends over part of the width of the said packaging400, being interrupted at the side welds 430.

As is shown in FIGS. 27 a, 28 a and 28 b, provision may be made for atleast one welded side edge 430 of the packaging 400 to comprise a notch431 for initiating opening located between two scored lines. Accordingto the embodiment shown in FIG. 28 a, the scored lines 432, 433 startdirectly from the notch 431 for initiating opening. As a variant, thescored lines could extend up to the edge of the packaging, therebysurrounding the initiating notch. In contrast, according to theembodiment shown in FIG. 28 b, the scored lines 432, 433 start from thewelded edge 430; there is therefore an unscored gap between the notch431 for initiating opening and the scored lines 432, 433.

The notch 431 for initiating opening promotes tearing of the materialsforming the packaging. More particularly, the tear initiated at thenotch 431 for initiating opening is propagated in the weld region 430 inthe direction of the opposite weld 410. This tear propagates over eachof the walls of the packaging until it encounters one of the two scoredlines 432 or 433 provided on the inner face of each wall of thepackaging. The tear continues along this scored line and guides theopening of the said packaging up to the opposite side, as is moreparticularly shown in FIG. 27 b.

As is more particularly shown in FIG. 29, the scored lines according tothe invention may be produced on a film which is wound on reels 3 andcontinuously fed for manufacturing several packagings. The deviceproducing the scored lines is shown schematically and is referenced 1.As is shown on the film 10, once the film has been scored in severalparticular locations, it will be wound on a reel 3 for subsequent use onpackaging machines or machines for manufacturing empty packagings.

Provision may also be made to produce these scored lines, as shown moreparticularly in FIG. 30, directly on the packaging machine or themachine for manufacturing empty packagings between the operation ofunwinding the reels 3 of film and welding the sides of the packagings.The device producing the scored lines is also shown schematically and isreferenced 1. The arrow referenced 2 indicates the direction towards therest of the packaging machine or the machine for manufacturingpackagings.

Moreover, it is preferable to avoid scored lines in the form ofperforations of the layer 12 made by teeth or needles before laminatingthe layers of film 10 if the latter is wound on reels before making thepackagings. This is because the perforation causes a local deformationof the film which causes lifting of the edges around each hole. This hasthe effect of creating an irregular winding of the film on the reel withcreation: of a swelling at the perforations and the risk of delaminatingthe film layers around the holes. In this case, it is thereforeappropriate to prefer scored lines which do not completely pass throughthe layer 12.

It is particularly advantageous that a groove, whether continuous ordiscontinuous, forming a scored line is bordered by a bead on only oneside. The bead provides the plastic material layer with reinforcedstrength along the groove. If a wall of the packaging has this scoredline close to one of its edges, the fact of arranging the bead on theside away from this edge prevents, during opening of the packaging alongthe scoring, the tear leaving the scored line and prevents itpropagating towards this opposite side of the packaging where thefoodstuffs are located, which would then risk them being accidentallyspilled. However, it is even more advantageous for there to be at leasttwo scored lines in the same wall of the packaging and for these to runclose to each other as in the example of FIG. 27 a. In this case, byforming the beads essentially along each scored line on the side whichis away from the other scored line, as is shown in FIG. 20, the beadsprevent the tear, during opening of the packaging, from moving away fromthe scored line towards the side having the beads. The result of this isthat the tear propagates only along the scored line or is deflectedtowards the other scored line along which the tear then continues, andso on and so forth. In other words, the tear for opening the packagingpropagates only between the two scored lines.

Similar advantageousness are obtained in case a groove, whethercontinuous or discontinuous, forming a scored line is bordered by a beadon each side of the groove, the beads being asymmetrical. The term“asymmetrical beads” refers to beads of which one has a height greaterthan the other with respect to the surface of the film. It refers alsoto a bead having a cross-sectional area being greater than thecross-sectional area of the other of the said beads (the cross-sectionalareas being considered perpendicular to the scored line). The beadhaving the greatest height or, more generally, the bead having thegreatest cross-sectional area increases the mechanical strength of theplastic material layer along the scored line to a greater extent withrespect to the other bead. Thus, the bead with greatest height or moregenerally the bead having the greatest cross-sectional area—whichprovides the greatest mechanical strength to the plastic layer along thescored line—can be arranged on the same side of the groove as describedpreviously in case of a single bead formed along each scored line andprovides a similar barrier effect to the tear propagation along thescored line. Therefore, it is preferable that the highest bead is atleast 30%, preferably at least 50%, more advantageously at least 100%,higher than the other bead. More generally, it is preferable that thebead of greatest cross-sectional area is at least 30%, preferably atleast 50%, more advantageously at least 100%, greater than thecross-sectional area of the other bead. The defined heights orcross-sectional areas can of course be obtained with a device accordingto the invention by defining accordingly the cross-section of theflowing ribs as already described.

Of course, the present invention is not limited to the examples and tothe embodiments described and shown, but it is capable of many variantsaccessible to a person skilled in the art. In particular, the devices ofFIGS. 10 to 21 use plastic flow by ultrasound which can be removed toproduce the scored line solely by cutting the material of the layer 12.To do this, the sonotrode just has to be replaced with a cylindricalroller or a flat plate in the case of FIG. 10, this roller or this plateserving to press the film 10 against the scoring wheels 51 a, 51 b.Likewise, the sonotrode in the case of FIG. 15 may be replaced with aflat plate pressing the film 10 against the shoes 71 a, 71 b. Of course,it is then preferable to alter the profile of the ribs so that they cutin a manner similar to the device of FIG. 2.

The device of FIGS. 2 to 14 may also use plastic flow of the material ofthe layer 12 outwards from the groove by heating, for example, theroller 22 to a temperature such that the ribs 26 a, 26 b reach atemperature which is high enough to make the material of the layer 12flow plastically. The profile of the ribs may then be altered in amanner similar to those 52 a of FIG. 11. Nevertheless, plastic flow byultrasound is more advantageous since the metal parts of the tooling,that is to say the ribs, remain cold enough so as not to be contaminatedby the material of the layer 12, the melting point of the latter notbeing exceeded.

Of course, application of the invention is not limited to the film ofthe type taken as an example. It is applicable to any film having aplastic layer in which it is desired to form the scored line or lines.In particular, it can be applied to films which do not have an aluminumcentral layer or else to single-layer plastic films. Of course, if thewalls of the packaging are made from a single-layer film, the scoredlines will not be produced in the form of perforations so as, to ensurethe packaging is sealed.

The devices of the invention may operate not only directly on amultilayer film having a plastic layer, such as for example that of FIG.1, but also on a plastic layer before assembly with other layers inorder to form the multilayer film. In the latter case, the devicesaccording to the invention, including those using plastic flow byultrasound, make it possible to produce scored lines in the form ofperforations in this plastic layer without risk of damaging otherlayers.

Moreover, with respect to the devices of FIGS. 2 to 14, the ribs may notonly be arranged in a radial plane of the, roller 22 or scoring wheel 51a, 51 b, but may also extend transversely along any line for the purposeof forming, for example, curved scored lines. However, it is preferablethat the ribs are arranged on the circumference of the roller or scoringwheels so as to provide a progressive plastically flowing out of thematerial to form beads on the surface of the plastic material layer whenproviding the scored lines with the flowing technology. Therefore, it ispreferable that the ribs do not extend axially on the circumference ofthe roller or scoring wheels. Indeed, if the ribs extend axially on thecircumference of the scoring wheels, the sonotrode undergoes energybursts each time a rib faces the sonotrode. These energy bursts can bedetrimental to the sonotrode. Further, the material of the film layerstends to be compressed which may be detrimental to the desiredproperties of the layers and the plastic material is not necessarilyflowed plastically out of the layer in order to form bead(s).Furthermore, the sonotrode would have to be as wide as the rib orseveral smaller sonotrodes would have to be located contiguously tocover the width of the rib, but the

Although the film has been described as running with respect to thedevice, and advantageously as running continuously with respect to thedevice, it is also possible according to the invention to have the filmstationary at the moment of producing the scored line in order to allowthe displacement, for example by translation, of a tool bearing theprojection, towards the film.

1. A device for producing at least one scored line in at least oneplastic material outer layer of a film, comprising: a bearing surfacefor the film; and at least one projection for forming the scored line bypenetration of the projection into said plastic material layer when thefilm is in position against said bearing surface.
 2. The deviceaccording to claim 1, in which the projection is arranged on a support,the scored line being formed by relative travel of the film with respectto the support.
 3. The device according to claim 1, in which theprojection is capable of incising the plastic material layer.
 4. Thedevice according to claim 1, in which the projection causes the plasticmaterial of the said layer to flow along the scored line in order toform a bead on the said layer along at least one side of the scoredline.
 5. The device according to claim 4, in which the projection has anasymmetrical cross section.
 6. The device according to claim 4, in whichthe projection causes the formation of a bead on the surface of the saidplastic material layer along just one side of the scored line.
 7. Thedevice according to claim 4, in which the projection causes the plasticmaterial of the said layer to flow along the scored line in order toform a bead on the said layer along each side of the scored line, theprojection causing more plastic material to be flowed along one side ofthe scored line than along the other side of the scored line.
 8. Thedevice according to claim 4, in which the projection causes the plasticmaterial to flow in cooperation with ultrasound.
 9. The device accordingto claim 8, comprising: an anvil, and a sonotrode for applyingultrasound vibrations to the film when the film is compressed betweenthe sonotrode and the anvil, in which the projection is arranged on saidanvil.
 10. The device according to claim 9, in which the bearing surfaceis arranged on the anvil.
 11. The device according to claim 9, in whichthe anvil is a wheel mounted so as to rotate, the projection forming arib arranged on the circumference of the wheel, the rib not extendingaccording to the axial direction of the wheel.
 12. The device accordingto claim 9, in which the projection is arranged on a support, the scoredline being formed by relative travel of the film with respect to thesupport, and the projection has a straight elongate shape in the rundirection of the film.
 13. The device according to claim 12, in whichthe projection has a cross section with a flat apex parallel to thebearing surface.
 14. The device according to claim 2, in which thesupport is a roller mounted so as to rotate, the projection beingarranged on the circumference of the roller.
 15. The device according toclaim 14, in which the projection is arranged on the circumference of aring, the said ring being mounted on the roller.
 16. The deviceaccording to claim 15, in which there is a clearance between the ringand the roller taken at ambient temperature, a heating element making itpossible to clamp the ring on the roller by expansion.
 17. The deviceaccording to claim 14, in which the bearing surface is defined by thecircumference of a second roller, the axis of which is parallel to thefirst roller.
 18. The device according to claim 17, in which the firstroller has running tracks tensioned against the second roller. 19-45.(canceled)
 46. The device according to claim 12, in which the height ofthe projection increases in the run direction of the film.
 47. Thedevice according to claim 12, in which the width of the projectionincreases in the run direction of the film.
 48. The device according toclaim 12, in which the width and the height of the projection increasesin the run direction of the film.